The present invention relates generally to medical devices and more particularly to an ablation instrument for isolating tissue, such as a tumor.
Various types of ablation techniques have been used to treat tumors in a patient. For example, one type of ablation technique involves using a bipolar electrode connected to a bipolar energy generator. Typically, a bipolar electrode has two poles that are spaced away from each other. Applying a charge to the poles from the bipolar generator causes tissue adjacent the poles to heat up. By adjusting the charge from the bipolar generator, the adjacent tissue can be heated to such a degree that a region of adjacent tissue is burned and killed. One type of bipolar electrode that is used to treat tumors is formed in the shape of a loop. Once the electrode is energized, the looped electrode can then be rotated around the tumor in order to burn and kill the tumor tissue.
However, several problems remain with existing ablation techniques. For example, one problem is that it can be difficult to fully kill the tumor tissue without causing excessive damage to surrounding healthy tissue. This can have several negative consequences. In particular, if the energy is adjusted to minimize damage to surrounding healthy tissue, all of the tumor tissue may not be killed. For example, when the bipolar electrode has a circular shape, tumor tissue located closer to the electrode absorbs more heat, but tumor tissue located farther from the electrode absorbs less heat. In other words, tumor tissue located at the center of the circular electrode may not be heated sufficiently to kill the tumor tissue at the center. This situation can allow the surviving tumor tissue to continue to grow, which eventually can result in recurrence of the tumor or metastasis of the tumor tissue.
On the other hand, adjusting the energy of the bipolar electrode higher to ensure a higher percentage of killed tumor tissue also results in more healthy tissue being killed or damaged. Thus, physicians can be faced with a difficult and complex task of adjusting energy settings of bipolar electrodes to achieve maximum tumor ablation while minimizing damage to surrounding healthy tissue. This challenge can become even more difficult when a tumor is located close to a crucial organ. In this case, the energy settings may need to be set particularly low to avoid causing critical damage to the nearby organ. However, such low energy settings may be ineffective in treating the tumor.
Accordingly, the inventor believes it would be desirable to provide a new medical instrument for ablating tissue that may be used to increase control over the ablation region.